The present application relates to a reproducing apparatus, a reproducing method and a reproducing program wherein a caption can be displayed in response to an interactive operation of a user in accordance with a program recorded on a recording medium having a large capacity such as a Blu-ray Disc (registered trademark).
In recent years, the Blu-ray Disc standards have been proposed for a recordable disc type recording medium which can be removed from a recording and reproducing apparatus. According to the Blu-ray Disc standards, a disc of a diameter of 12 cm and a cover layer thickness of 0.1 mm is used as a recording medium while a blue-violet laser of a wavelength of 405 nm and an objective lens of a numerical aperture of 0.85 are used as an optical system, and a recording capacity of 27 GB (gigabytes) is achieved in the maximum. Where the Blu-ray Disk standards are adopted, a BS digital high definition broadcast in Japan can be recorded for more than two hours without suffering from deterioration of the picture quality.
As sources (supply sources) of AV (Audio/Visual) signals to be recorded on the recordable optical disc, those sources which supply an analog signal, for example, by an analog television broadcast and those sources which provide a digital signal such as, for example, a digital television signal beginning with a BS digital broadcast have been supposed. According to the Blu-ray Disk standards, standards which prescribe methods of recording AV signals from such broadcasts are available already.
On the other hand, development of a read-only recording medium on which a movie or music is recorded in advance according to derivative standards of the Blu-ray Disk at present is proceeding. A DVD (Digital Versatile Disc) is already popularized widely as a disc type recording medium for recording a movie or music. However, a read-only optical disc based on the Blu-ray Disk standards is different much from and superior to an existing DVD in that, by making the most of a large capacity, a high transfer rate and so forth of the Blu-ray Disk, high definition images can be recorded for more than two hours while maintaining high picture quality.
The standards for a read-only recording medium according to the Blu-ray Disk are hereinafter referred to as BD-ROM format (Blu-ray Disc Read-Only Format).
One of essential factors to a content to be recorded on a read-only recording medium is the caption. According to the BD-ROM format, a caption is displayed on a plane different from a plane on which a moving picture is displayed, and the plane on which a caption is displayed and the plane on which a moving picture is displayed are combined with each other to display the caption and the moving picture in an overlapping relationship with each other. For example, if the caption plane on which a caption is displayed is disposed in front of the moving picture plane on which a moving picture is displayed and the attribute of transparency is provided to a portion of the caption plane other than the caption, then image data for one image on which the caption is displayed on the moving picture can be constructed.
Japanese Patent Laid-open No. 2004-304767 discloses an apparatus and method wherein, based on the Blu-ray Disc standards (Blu-ray Disc Rewritable Format Ver. 1.0) which are recording and reproducing standards, planes on which a moving picture and a caption are displayed are provided such that a moving picture based on video data and a caption based on caption image data are displayed on one screen.
In the BD-ROM format, caption data for displaying a caption is defined as data which is recorded as text data on and provided together with a recording medium and as data which is recorded as graphics data formed from bitmap data on and provided together with a recording medium.
Where a caption is supplied as text data, the caption data is read in from a disc in advance, for example, upon starting of reproduction of the disc and is retained into a built-in memory of a player. Display of the caption data on the screen may be performed by reading in a font file recorded on the disc and using a font placed in the read in font file or by using a font built in the player in advance.
On the other hand, where a caption is supplied as graphics data, the graphics data (hereinafter referred to as caption image data) for displaying the caption is recorded as stream data on a disc together with video data or the like with information embedded therein which indicates the display time. The caption image data are reproduced from the disc as the video data are reproduced and successively embedded in a predetermined unit into a buffer built in the player. If the display time indicated by the display time information embedded in the caption image data comes, then the caption image data are read out from the buffer and displayed for each predetermined unit.
The unit of caption image data can be determined arbitrarily, for example, by the manufacturer side. For example, one sentence may be determined as one unit or one character may be determined as one unit such that characters are successively displayed. Further, the caption image data are not limited to data for displaying characters.
Further, the caption image data embedded in the buffer are abandoned from the buffer when they are read out from the buffer. In particular, the player side cannot know in advance when and by what amount caption image data are supplied thereto. Therefore, in order to assure the free region of the buffer, the caption image data read out for display are abandoned from the buffer.
Incidentally, according to the BD-ROM format, the on/off state of the caption display can changed over during reproduction by a user operation or using an interactive button. When a caption display off instruction is received, then the caption display is erased by replacing data of a caption displaying portion of the caption plane with data of the transparent attribute. The user operation is an operation by a user, for example, of a remote control commander.
However, caption image data are abandoned from the buffer when they are read out from the buffer for display as described hereinabove, and this gives rise to the following problem. In particular, if a caption display off instruction is issued with regard to a caption being currently displayed, then even if a caption display on instruction is issued again, the caption display may not be re-started immediately.
This is because, since caption image data are abandoned from the buffer at the timing of display thereof, even if a caption display on instruction is issued again after a caption display off instruction is issued, caption image data to be displayed does not exist in the buffer. In this instance, no caption is displayed at all till a timing of next caption display. Where the caption for which the caption display off instruction is issued is the last caption for the moving picture, no caption is displayed until reproduction of the moving picture ends.
This is described more particularly with reference to FIGS. 32A to 32D. FIG. 32A illustrates display timings of caption image data #N (#1 to #5). FIG. 32B illustrates states of the caption image data #N in the buffer. FIG. 32C illustrates the caption image data #N displayed at the display timings. FIG. 32D illustrates the caption image data #N displayed actually when caption display off and on instructions are issued by the user. Caption image data stored in the buffer are successively displayed at the individual display timings and abandoned from the buffer (refer to FIGS. 32A to 32C).
As seen in FIG. 32D, the caption is erased in response to the caption display off instruction, and then at a point of time at which the caption display on instruction is issued in response to a user operation, the caption image data #3 to be displayed upon issuance of the caption display on instruction is abandoned from the buffer already (refer to FIG. 32B). Accordingly, no caption is displayed within a period from the timing of the caption display on instruction to the display timing of the next caption image data #4.
Accordingly, depending upon the authoring situation of the disc, it is not sometimes desirable to change over the on/off state of the caption display through a user operation. Therefore, according to the BD-ROM format, such control as to cause caption display to be performed compulsorily irrespective of the user operation for on/off of the caption display is defined.
Further, in the BD-ROM format, a plurality of, for example, two, captions can be displayed independently of each other on one screen. For example, captions of two different languages can be displayed individually on one screen. The above-described control of whether or not caption display is to be performed compulsorily can be applied to each of the two captions independently of each other. As an example, on/off of display of one of two captions displayed on a screen can be controlled through a user operation while the other caption is displayed compulsorily irrespective of the user operation.
Here, it is assumed that, as seen in FIG. 33A, a caption #1 according to compulsory display setting by which caption display is performed compulsorily irrespective of a user operation and another caption #2 according to non-compulsory display setting by which on/off of the character display is changed over in response a user operation are displayed simultaneously on a screen 200. If a caption display on instruction is issued through a user operation, for example, through an operation of a remote control commander by the user in the state illustrated in FIG. 33A, then both of the caption #1 and the caption #2 are displayed.
Here, if a caption off instruction is issued through another user operation, then the display of the screen 200 changes to such a degree that the caption #1 based on the compulsory display setting remains displayed while the display of the caption #2 based on the non-compulsory display setting disappears, for example, as seen in FIG. 33B.
Now, it is assumed that a caption display on instruction is issued in response to a further user operation in the state of FIG. 33B. When the user issues the caption display on instruction, the user expects that the display of the screen 200 returns to the display illustrated in FIG. 33A wherein both of the caption #1 and the caption #2 are displayed.
However, there is a problem that, depending upon the authoring situation according to the caption #1 and the caption #2, there is the possibility that, even if a caption display on instruction is issued in the state of FIG. 33B, the display of the screen 200 may be placed into a state wherein the caption #2 is not displayed but only the caption #1 is displayed similarly as illustrated in FIG. 33B.